This invention refers to electric fuses having a tubular casing of electric insulating material which is closed on the ends thereof by ferrules, or terminal caps. The ferrules, or terminal caps, are conductively interconnected by one or more fusible elements. The ends of a fusible element or of fusible elements are generally conductively connected to the ferrules either by spot welds, or by solder joints. There are a great many ways of establishing electrically conductive joints. Solder joints of the kind under consideration are classified into two classes, of which one class is referred to as blind solder joints. Blind solder joints are generally not visible. Therefore fuses having blind solder joints have generally a better appearance than fuses having solder joints which are visible from the outside thereof. As a rule, fuses having blind solder joints are less reliable than fuses having visible solder joints because, generally, the soldering process cannot be observed while the solder joints are made, and because a defect in a blind solder joint may not readily be discovered by quality control methods. Conventional blind solder joints have a high ratio of non-satisfactory joints to satisfactory joints. This is also due to the fact that when making conventional blind solder joints the parts to be soldered together cannot be held in engagement under pressure while the joint is made.
It is, therefore, the prime object of this invention to provide electric fuses including blind electrically conductive joints between the ferrules and the ends of the fusible element or elements which fuses are not subject to the above limitations. Another object of this invention is to provide fuses wherein electrically conductive joints formed between the ends of the fusible element or elements and the ferrules are not visible from the outside of the fuse structure and can be made cost effectively with a high degree of reliability.
Other objects and advantages of the invention will become more apparent as this specification proceeds.